1/* Store current floating-point environment and clear exceptions.
2 Copyright (C) 1997-2022 Free Software Foundation, Inc.
3 This file is part of the GNU C Library.
4
5 The GNU C Library is free software; you can redistribute it and/or
6 modify it under the terms of the GNU Lesser General Public
7 License as published by the Free Software Foundation; either
8 version 2.1 of the License, or (at your option) any later version.
9
10 The GNU C Library is distributed in the hope that it will be useful,
11 but WITHOUT ANY WARRANTY; without even the implied warranty of
12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 Lesser General Public License for more details.
14
15 You should have received a copy of the GNU Lesser General Public
16 License along with the GNU C Library; if not, see
17 <https://www.gnu.org/licenses/>. */
18
19#include <fenv.h>
20#include <unistd.h>
21#include <ldsodefs.h>
22#include <dl-procinfo.h>
23
24int
25__feholdexcept (fenv_t *envp)
26{
27 /* Store the environment. Recall that fnstenv has a side effect of
28 masking all exceptions. Then clear all exceptions. */
29 __asm__ volatile ("fnstenv %0; fnclex" : "=m" (*envp));
30
31 /* If the CPU supports SSE we set the MXCSR as well. */
32 if (CPU_FEATURE_USABLE (SSE))
33 {
34 unsigned int xwork;
35
36 /* Get the current control word. */
37 __asm__ ("stmxcsr %0" : "=m" (envp->__eip));
38
39 /* Set all exceptions to non-stop and clear them. */
40 xwork = (envp->__eip | 0x1f80) & ~0x3f;
41
42 __asm__ ("ldmxcsr %0" : : "m" (*&xwork));
43 }
44
45 return 0;
46}
47libm_hidden_def (__feholdexcept)
48weak_alias (__feholdexcept, feholdexcept)
49libm_hidden_weak (feholdexcept)
50

source code of glibc/sysdeps/i386/fpu/feholdexcpt.c